Fan blade compliant shim

Abstract

A compliant shim for use between the root of a gas turbine fan blade and a dovetail groove in a gas turbine rotor disk to reduce fretting therebetween. The compliant shim has first and second slots for engaging tabs extending from the fan blade root. The slots and tabs cooperate to hold the shim during engine operation. An oxidation layer covers the compliant shim.

What is claimed is:  
     
       1. A rotor assembly for a gas turbine engine, comprising: 
       a disk having along its periphery at least one dovetail groove;  
       a blade having an airfoil portion and a root portion, said root portion contoured to be received within said dovetail groove and having an inner surface that extends axially from a leading edge to a trailing edge, said inner surface having first and second tab members extending inward therefrom to define a gap between said inner surface and a base of said groove; and  
       a compliant shim disposed in said gap and having a first slot for engaging said first tab and a second slot for engaging said second tab.  
     
     
       2. The assembly of  claim 1  wherein said shim has a flat base and two spaced apart walls extending therefrom. 
     
     
       3. The assembly of  claim 2  wherein each of said walls is curvilinear. 
     
     
       4. The assembly of  claim 3  wherein said walls have first portions that curve away from each other, second portions that curve towards each other and third portions that curve away from each other. 
     
     
       5. The assembly of  claim 1  further comprising a oxidation layer over at least a portion of said shim. 
     
     
       6. The assembly of  claim 5  wherein the thickness of said oxidation layer is in the range 0.0002-0.0003 inch. 
     
     
       7. The assembly of  claim 5  wherein said disk and blade are made of titanium and said shim is made of a cobalt alloy. 
     
     
       8. The assembly of  claim 5  wherein said disk and blade are made of titanium alloy and said shim is made of cobalt alloy. 
     
     
       9. A compliant shim for use between a fan blade and a rotor disk comprising a base portion extending from a first end to a second end, said first and second ends each having a slot for engaging a corresponding tab extending from said blade and two curvilinear spaced apart walls extending outward from said base to define a space for receiving a root portion of said blade. 
     
     
       10. The compliant shim of  claim 9  wherein said walls have first portions that curve away from each other, second portions that curve towards each other and third portions that curve away from each other. 
     
     
       11. The compliant shim of  claim 10  further comprising a oxidation layer over said base portion and said walls. 
     
     
       12. The compliant shim of  claim 11  wherein the thickness of said oxidation layer is in the range of 0.0002-0.0003 inch. 
     
     
       13. A rotor assembly for a gas turbine engine, comprising: 
       a disk having along its periphery at least one dovetail groove;  
       a blade having an airfoil portion and a root portion, said root portion contoured to be received within said dovetail groove and having an inner surface that extends axially from a leading edge to a trailing edge, said inner surface having first and second tab members extending inward therefrom to define a gap between said inner surface and a base of said groove;  
       a compliant shim disposed in said gap and having a first slot for engaging said first tab and a second slot for engaging said second tab; and  
       an oxidation layer over at least a portion of said shim.  
     
     
       14. The assembly of  claim 13  wherein said shim has a flat base and two spaced apart walls extending therefrom. 
     
     
       15. The assembly of  claim 14  wherein each of said walls is curvilinear. 
     
     
       16. The assembly of  claim 15  wherein said walls have first portions that curve away from each other, second portions that curve towards each other and third portions that curve away from each other. 
     
     
       17. The assembly of  claim 13  wherein the thickness of said oxidation layer is in the range 0.0002-0.0003 inch. 
     
     
       18. The assembly of  claim 13  wherein said disk and blades are made of tanium and said shim is made of a cobalt alloy. 
     
     
       19. The assembly of  claim 13  wherein said disk and blade are made of titanium alloy and said shim is made of a cobalt alloy. 
     
     
       20. A compliant shim for use between a fan blade and a rotor disk comprising a base portion extending from a first end to a second end, said first and second ends each having a slot for engaging a corresponding tab extending from said blade and two curvilinear spaced apart walls extending outward from said base to define a space for receiving a root portion of said blade, said shim further comprising an oxidation layer over said base portion and said walls. 
     
     
       21. The compliant shim of  claim 20  wherein said walls have first portions that curve away from each other, second portions that curve toward each other and third portions that curve away from each other. 
     
     
       22. The compliant shim of  claim 20  wherein the thickness of said oxidation layer is in the range of 0.0002-0.0003 inch.